This invention relates generally to ultrasonic probes, and more particularly to dual phased array ultrasonic probes that measure the thickness of materials.
Ultrasonic testing is a type of non-destructive testing that is used to inspect test object in order to identify and/or characterize defects, flaws, and other anomalies in the test object. Testing equipment that is used in ultrasonic testing generally includes a probe that sends and receives signals, a test instrument that operates the probe, and a cable that transmits information between the probe and the test instrument.
The probe incorporates transducer elements that are constructed of piezoelectric materials that are responsive to certain stimuli in a manner conducive to non-destructive testing. For example, certain transducer elements that are found in the probes generate acoustic waves in response to electrical waveform pulses that are applied to electrodes connected to the element. These elements are also responsive to acoustic waves, such as those acoustic waves that are reflected from the test object. This generates a voltage difference across electrodes that are connected to the element. For purposes of ultrasonic testing, transducer elements are used to transmit acoustic waves into the test object, transducer elements are used to capture the reflection of those acoustic waves, and the resultant voltage differences caused by the reflected waves are processed in order to analyze the test object.
While many probes utilize the same transducer elements to transmit and to receive the acoustic waves, such probes are typically not suited to measure the thickness of materials that are corroded because of the noise, e.g., the backscattered noise, which is generated by the corrosion. Instead, probes that are used to measure the thickness of corroded materials typically have a pair of transducer elements, one that transmits the acoustic wave to the test object, and one that receives the reflected acoustic waves from the test object. Probes that are of the type suited to measure the thickness of corroded materials, however, are not often compatible with test objects that have large surface areas.
One reason for this is because the field of view of these probes is much smaller than the area of interest of the test object. This makes testing large areas of interest highly inefficient, and in many cases very costly. Moreover, because the ratio of the field of view of the probe to the area of interest of the test object is small, the likelihood increases that defects in the area of interest will be missed because the defects may not fall within the field of view of the probe.
Therefore, it would be advantageous to have an apparatus that can provide highly accurate measurement of material thickness for large areas of interest. It would also be advantageous to have an apparatus that can measure the thickness of corroded materials, while being configured in a manner so as to improve the inspection of test objects by reducing both the inspection costs, and the likelihood that defects are missed during the inspection.